Activated sludge-loaded polyvinyl alcohol microparticles for starch wastewater treatment in an airlift bioreactor

Emulsification followed by freezing and thawing cycles was applied to produce poly(vinyl alcohol) (PVA) microparticles and to simultaneously immobilize activated sludge. Activity of the obtained microparticles (～400 μm in diameter) was evaluated in glucose syrup solutions and heat-pretreated wastewater from a starch factory by measurements of permanganate index (COD _Mn ) reduction. The reaction followed first-order kinetics, revealing slight mass transfer limitations in PVA microparticles as determined from the kinetic rate constant that was ～35% lower than that in the freely suspended activated sludge culture. Yet, efficiency of the microparticles increased almost five-fold in a laboratory airlift bioreactor operating either in batch or continuous regimes. Over 19 days of operation under high organic loadings in the industrial wastewater (～100 kgCOD m^?3 d^?1), PVA microparticles (12.4% volume fraction) remained active and induced a decrease of over 90% of biodegradable COD _Mn at the hydraulic retention time of 8 h.     

Almost constant-time 3D nearest-neighbor lookup using implicit octrees

A recurring problem in 3D applications is nearest-neighbor lookups in 3D point clouds. In this work, a novel method for exact and approximate 3D nearest-neighbor lookups is proposed that allows lookup times that are, contrary to previous approaches, nearly independent of the distribution of data and query points, allowing to use the method in real-time scenarios. The lookup times of the proposed method outperform prior art sometimes by several orders of magnitude. This speedup is bought at the price of increased costs for creating the indexing structure, which, however, can typically be done in an offline phase. Additionally, an approximate variant of the method is proposed that significantly reduces the time required for data structure creation and further improves lookup times, outperforming all other methods and yielding almost constant lookup times. The method is based on a recursive spatial subdivision using an octree that uses the underlying Voronoi tessellation as splitting criteria, thus avoiding potentially expensive backtracking. The resulting octree is represented implicitly using a hash table, which allows finding the leaf node a query point belongs to with a runtime that is logarithmic in the tree depth. The method is also trivially extendable to 2D nearest neighbor lookups.     

Unveiling Molecular Changes in Water by Small Luminescent Nanoparticles

Nowadays a large variety of applications are based on solid nanoparticles dispersed in liquids—so called nanofluids. The interaction between the fluid and the nanoparticles plays a decisive role in the physical properties of the nanofluid. A novel approach based on the nonradiative energy transfer between two small luminescent nanocrystals (GdVO₄:Nd³⁺ and GdVO₄:Yb³⁺) dispersed in water is used in this work to investigate how temperature affects both the processes of interaction between nanoparticles and the effect of the fluid on the nanoparticles. From a systematic analysis of the effect of temperature on the GdVO₄:Nd³⁺ → GdVO₄:Yb³⁺ interparticle energy transfer, it can be concluded that a dramatic increase in the energy transfer efficiency occurs for temperatures above 45 °C. This change is properly explained by taking into account a crossover existing in diverse water properties that occurs at about this temperature. The obtained results allow elucidation on the molecular arrangement of water molecules below and above this crossover temperature. In addition, it is observed that an energy transfer process is produced as a result of interparticle collisions that induce irreversible ion exchange between the interacting nanoparticles.     

Fuzzy linear model for production optimization of mining systems with multiple entities

Planning and production optimization within multiple mines or several work sites (entities) mining systems by using fuzzy linear programming (LP) was studied.LP is the most commonly used operations research methods in mining engineering.After the introductory review of properties and limitations of applying LP,short reviews of the general settings of deterministic and fuzzy LP models are presented.With the purpose of comparative analysis,the application of both LP models is presented using the example of the Bauxite Basin Niksic with five mines.After the assessment,LP is an efficient mathematical modeling tool in production planning and solving many other single-criteria optimization problems of mining engineering.After the comparison of advantages and deficiencies of both deterministic and fuzzy LP models,the conclusion presents benefits of the fuzzy LP model but is also stating that seeking the optimal plan of production means to accomplish the overall analysis that will encompass the LP model approaches.     

Application of feedforward neural network in the study of dissociated gas flow along the porous wall

This paper concerns the use of feedforward neural networks (FNN) for predicting the nondimensional velocity of the gas that flows along a porous wall. The numerical solution of partial differential equations that govern the fluid flow is applied for training and testing the FNN. The equations were solved using finite differences method by writing a FORTRAN code. The Levenberg–Marquardt algorithm is used to train the neural network. The optimal FNN architecture was determined. The FNN predicted values are in accordance with the values obtained by the finite difference method (FDM). The performance of the neural network model was assessed through the correlation coefficient (r), mean absolute error (MAE) and mean square error (MSE). The respective values of r, MAE and MSE for the testing data are 0.9999, 0.0025 and 1.9998 · 10^?5.     

Effects of liquid burn rate catalysts on Rheological Properties of High-Energy Composite Propellants

Effects of several liquid burning rate catalysts on rheological properties of composite rocket propellants on the basis of hydroxy-terminated polybutadiene as a binder and ammonium perchlorate as an oxidizer have been examined. Theoretical explanation of the observed effects of liquid catalysts on certain rheological properties of the mentioned propellants are given. Laboratory procedures for synthesis of used catalysts are described. The results of physico-chemical characterization of synthesized catalyst are also presented.     

GPS telemetry of energetic-technical and technological parameters at open pit mines

Application of GPS in mining and geology has proved to be of ever increasing importance since recently. GPS is used for positioning both researching and exploitation drill holes, mining facilities, equipment, machines, when monitoring slopes and falls, mining facilities dimensioning, navigation of machines, roads tracing, etc. The paper presents a pilot system for surveillance and monitoring of energetic and technological parameters at open pit mines, developed at the “Jazovnik” open pit mine for experimental purposes. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 4, pp. 90–94, July–August, 2008.     

Longitudinal air permeability of pinewood with beetle transmitted blue-stain

The mountain pine beetle epidemic is destroying an extensive volume of the lodgepole pine forests being one of the most commercially harvested trees in British Columbia. The purpose of this study was to test the permeability of wood of four different classes regarding the time of the beetle attack. The experiments used the ‘‘falling water’’ unsteady-steady method of measuring superficial air permeability. The results showed that the specific permeability is not significantly different between the infested classes tested. The same conclusion could be reached for comparisons of uninfected and infested wood.